Heretofore, an organophosphorus compound, a carbamate compound, a pyrethroid compound or the like has been used as an effective ingredient for an insecticide, but as this result, some insects have had a resistance to these insecticides in recent years. Therefore, it is demanded to provide an insecticide effective for these insects having a resistance. A pyridic compound of the formula (I) or its salt is disclosed in Japanese Patent No. 2994182, JP-A-10-195072, JP-A-11-180957, WO 98/57969, WO 00/35285, WO 00/35912, WO 00/35913, WO 01/9104, WO 01/14373 and the like.
Conventional pesticides have respectively characteristic spectrums and effects, but have some problems that the effects are sometimes unsatisfactory to certain pests, that their residual activities are sometimes poor and the effects are not satisfactorily maintained for a certain period of time, and that satisfactory pesticidal effects can not be practically achieved depending on applications. Also, even if there are some pesticides excellent in their pesticidal effects, they are demanded to be improved in respect of safety to fishes, crustacea and domestic animals and are also demanded to achieve a high pesticidal effect at a small dosage.